I have an upcoming job that requires file ready for output to a digital 8m x 3m monster print.

As I've never worked with that output size before, what is the recommended workflow?

Hi,

To give a meaningful response, one needs to know the printer/technology to be used for the actual output. Also important is to know the minimum and average viewing distance of that finished output, and how it is going to be mounted/displayed.

What may be relevant is the type of subject matter, and the customer's expectation (what are they achieving to accomplish) or prior experience (do they have an earlier or other quality level to compare with) with such a project.

Thanks guys. Yes, I would say view distances would be approx 5-10m. I'm guessing the printer might even ask for the unsharpened, non-resized image and go from there themselves. I just wanted to be prepared so I have some pre-knowledge. I have found a site which gives approx radius sharpening settings for different viewing distances. Good starting point

Thanks guys. Yes, I would say view distances would be approx 5-10m. I'm guessing the printer might even ask for the unsharpened, non-resized image and go from there themselves.

By your description of the desired output size, sounds like it may be printed on a grand format printer such as a roland. If so, this assumption might be correct, they may prefer the printer RIP to handle it, and often the results from that are pretty good.

When you say merged multi-layers images are you meaning stitching multiple images to get more resolution? Sounds like you may need it, not sure. Bart is better at figuring out that stuff than I am, think he has an online tool that helps with that as well.

By your description of the desired output size, sounds like it may be printed on a grand format printer such as a roland. If so, this assumption might be correct, they may prefer the printer RIP to handle it, and often the results from that are pretty good.

Hi Wayne,

That's why I was asking, we either have no control or we do, and if we do then we'd need to feed the right resolution for the process. Maybe they want one single file, maybe they need it as predefined panels, with (or without) overlap.

Quote

When you say merged multi-layers images are you meaning stitching multiple images to get more resolution? Sounds like you may need it, not sure. Bart is better at figuring out that stuff than I am, think he has an online tool that helps with that as well.

For normal quality, viewing distance 5 metres, and a D800 as camera, a single frame should allow 10.7 x 7.1 metres output size. That of course assumes good shooting technique and good postprocessing/sharpening/upsampling. If the subject allows, one can stitch for an even higher quality, but it might be wasted effort on many viewers.

I'll may add a module for multiple image stitches, but in its current state one can play with the sensor dimensions to get a feeling about what is required if a larger output size or higher quality is needed than a single image can provide.

Thanks again guys. Really great information. I will do some much needed learning on this topic. Yes, I was thinking of creating a merged panorama, and may even use a panoramic head to keep alignment issues to a minimum.

Yes, thankfully it is a static subject, an interior, so I probably can merge several frames.

On the subject of upsizing, should I use cc in graduated steps, or Lightroom, or use perfect resize? Or is another option more suitable.

On the subject of upsizing, should I use cc in graduated steps, or Lightroom, or use perfect resize? Or is another option more suitable.

Hi,

As my tool suggests for 8 metres wide output, "This output (7360 × 4912 px @ 23.368 PPI) still needs to be resampled to the native PPI of your output device." This resampling is either handled by the RIP of the Large Format output modality, or you need to know the native resolution of the output device to avoid resampling of your input file by fast but substandard resampling algorithms of the printer driver. Resampling also undermines any effort of earlier output sharpening, which should always be the last step at native output resolution.

Assuming (!) the printer requires 300 PPI native resolution, then you'd need to upsample by a factor of 300/23.368 = 12.838x .That typically is too much for Photoshop to handle well, and you'd need special software (I prefer PhotoZoom Pro over Perfect resize) to make the best of that. It would also produce a huge output file (larger than many file formats can accommodate), and output sharpening at that size also takes time and lots of memory / processing power. One would also need to reduce to 8-bit/channel output, therefore preferably already in the output device's profiled colorspace. Consulting with the printer operator is inevitable.

If the printing operation doesn't allow such detailed consultation, it may be better to provide higher resolution input material, i.e. properly stitched files, so that less resampling is required and less can go wrong at their end.

Haha...yes, my math taxed brain was boggled by the numbers. I knew it was big, but I guess it will all become clear. I understand the 24ppi re viewing distance, but the translating that to the output printer is where I'm a bit lost I think.

Can I assume that that 12.838x (7360 × 4912)px? Or am I missing something? Many thanks

Hi,

Yes, if treated as a single file it becomes 94488 x 63060 pixels (6 GB at 8-bit/channel). A regular TIFF is limited to 2 or 4 GB maximum, so a Big TIFF or other file type needs to be used, or the resampling result must be fed directly to the print pipeline. One can of course do several things about that.

One thing is to not upsample to the native resolution of the output device. But that leaves part of the resampling to the output driver / RIP, and it changes any output sharpening done to the smaller size output file.

Another thing is to do the correct upsampling and output sharpening at the native output size, but subdivide the image in tiles. Depending on the printing process those sections can then be recombined at printing time, e.g. by printing the sections edge to edge, or first composite them to a single file before printing, but that depends on the RIP or printer driver's capabilities.

The capabilities and preferences of the printer operator will dictate which route to take. Also the mounting method, single image, panels, banners, frames, support materials, transportation method, etc., etc., all play a role.

Thankyou for the very clear explanation. That makes good sense. Yes, I imagine I will send a high res file to the printer, who will handle upsizing 'live' at their end. I will get in touch with them next week. Appreciate the tips and advice. As you say, tiles is also another way to get around the GB filesize limit on tiffs.

As an update, the client is happy with the results. Final image actually came down a little in res to about 6500px wide, due to their cropping requests. Yet to work with the prepress guys to establish which software/technique to use for upsizing. But they seem to be ok with what I've provided. Pano head worked great, but to be honest, a couple of landscape pops stitched would have kept them happy.

It was a 66 frame stitched panoramic of the Chicago skyline shot with a 39mp Phase One P45+ system and a "cherry picked" 80mm Phase One lens. The camera was mounted in a Really Right stuff multi-row panoramic rig Supported by a Foba ASMIA head on a Gitzo 500 series (aluminum tripod ballasted by a lot of sand bags. I shot with a lot more overlap than is usually suggested overlap. Technically I might have shot with less overlap and needed fewer frames but when I was the stitched 66 layer file

The raw files were processed in Capture One and the stitching was done by PTGui Pro. It was output as a layered PSB format document and opened in Photoshop (CS5 at the time, I now use Photoshop CC) and nearly every layer's mask needed editing to resolve glitches due to movement of a person, automobiles, a train, tree leaves (it was windy), or boat.

As I recall it was printed at 150~180 dpi which was on the bottom edge of acceptable resolution. Stiil, although shot from 66 stories up the printed image resolved details in bricks and people's shirts who were probably a tenth to an eighth of a mile away

Thank you for sharing that. That is very interesting information. To be honest, I learnt from my own shoot: I would probably lean more towards your approach next time, where I might even use a slightly longer focal length, and take more images for my stitched composite. I was using a Nikkor 14-24 at 14, and distortion is pretty well controlled, but of course, there is lots of curvature when doing a pano shot. I used CC for stitching, but will probably get PTgui pro eventually. The client has specified 90-150dpi, but in reality, we are probably going to run with 75, but that is going to be out of my hands. I'm upsizing to 30000px wide in Perfect Resize (as I have that) as a comparison of PR and CC (one step upsizing) showed PR was slightly superior for that type of quick upsize work. The client will then complete the upsizing to the desired print size. They are going to test on an A4 print to get a good feel for the pixel density at the final size.